Hadith 1:177
Hasan (Zubair `Aliza'i)
Abu Dharr reported God’s messenger as saying, “He who separates himself a handbreadth from the community has cast off the rope of Islam from his neck.” Ahmad and Abu Dawud transmitted it.
وَعَنْ أَبِي ذَرٍّ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ فَارَقَ الْجَمَاعَةَ شبْرًا فقد خلع رقة الْإِسْلَامِ مِنْ عُنُقِهِ» . رَوَاهُ أَحْمَدُ وَأَبُو دَاوُدَ
Original Reference: Mishkat al-Masabih 185